Process for the hydrocracking of a rich-aromatics distillate to btex and hydrocracking catalysts, methods for their preparation and use

Abstract

The present application relates to the field of hydrocracking, in particular to a method for preparing BTX by hydrocracking of aromatic-rich distillate oil, a hydrocracking catalyst and a preparation method and application thereof, the catalyst comprising the following components: a) 0.01% to 1.5% Pd; b) 50% to 90% ZSM-5; c) 5% to 50% beta zeolite; d) 5% to 20% binder; and the catalyst coke content is 0.1% to 3% of the catalyst weight. ‑1 The catalyst has high stability under the process conditions of a pressure of 2 to 6 MPa, a temperature of 300 to 500 DEG C and a space velocity of 0.8 to 4 h-1.

Description

Technical Field

[0001] This invention relates to a hydrocracking catalyst, its preparation method and application, and a method for producing BTX by hydrocracking of aromatic-rich distillate oil. Background Technology

[0002] Light, aromatic-rich distillate oils mainly refer to light oils with a distillation range below 300℃, primarily composed of hydrocarbons and aromatics, such as cracked C9 hydrocarbons. + Ethylene tar, coal tar, and light cracked diesel oil are examples of oils that primarily consist of monocyclic and polycyclic aromatic hydrocarbons. These oils have short side chains, high carbon-to-hydrogen ratios, high sulfur and nitrogen content, high density, low cetane numbers, and poor stability, making them unsuitable for meeting clean fuel standards. They require highly demanding hydrogenation processes to be used as blending components in clean diesel oil, but this process is costly and economically inefficient.

[0003] Effective July 1, 2023, according to the "Announcement on the Implementation of Consumption Tax Policies for Some Refined Oil Products," the state levies consumption tax on mixed aromatics, heavy aromatics, mixed C8 hydrocarbons, stabilized light hydrocarbons, light oil, and light coal tar as naphtha. This further increases the cost of using light, aromatic-rich distillate oils as petroleum products.

[0004] Previously, many domestic and international manufacturers used rich aromatic distillate oils to produce aromatic solvent oils. Domestically, these were mainly private companies such as Jiangsu Hualun Chemical Co., Ltd. and Nantong Runfeng Petrochemical Co., Ltd. Internationally, major producers included ExxonMobil (USA), Shell (Netherlands), and Maruzen Petroleum Co., Ltd. (Japan). With the implementation of new domestic regulations in 2023, the already over-produced aromatic solvent oil industry faced further difficulties, with rising costs and declining profits, leading to potential industry losses.

[0005] Therefore, developing the chemical utilization of aromatic-rich distillate oils and fully leveraging the aromatic resource advantages of these oils to produce light aromatics is the best option for high-value-added utilization of such oils.

[0006] Light aromatic hydrocarbons, such as benzene, toluene, and xylene, are important basic chemical raw materials with a wide range of applications. They can be used as organic chemical raw materials in the petrochemical industry, as well as as the main raw materials for the production of synthetic fibers, synthetic rubber, synthetic resins, and various fine chemical products.

[0007] To fully utilize the aromatic resources in aromatic-rich distillate oil, it is necessary to convert low-value-added aromatic-rich distillate oil into BTX through catalytic conversion technology, thereby realizing the chemical utilization of aromatic-rich distillate oil.

[0008] Catalytic conversion technology for aromatic distillate oils has been gradually industrialized since the 1970s. Currently, mature pretreatment technologies for catalytic cracking feedstocks are available, including: UOP's VGO Unionfining and APCU (partial conversion hydrocracking) technologies, Haldor Topsøe's Aroshift technology, Chevron's VGO Hydrotreating technology, Exxon's VGO Hydrodesulfurization technology, IFP's T-star technology, and Mobil, AKZO, and Kellogg's MAKfinging technology. To further improve product quality and conversion rates, catalytic feedstock hydrotreating processes are gradually shifting from traditional hydrodesulfurization (HDS) to moderate hydrocracking (MHC) to enhance denitrification, residual carbon, and polycyclic aromatic hydrocarbon saturation.

[0009] These technologies generally employ hydrosaturation and hydrocracking processes, which not only result in high hydrogen consumption for aromatic-rich cracked distillates with high aromatic content but also waste valuable aromatic resources. Some technologies, such as CN102234539A, also involve completely saturating the aromatics in the aromatic-rich oil before hydrocracking to produce gasoline and diesel, which has high production costs and is not economical.

[0010] Based on technologies such as hydrodesulfurization (HDS) and denitrification (HDN) of distillate oil, optimization and innovation are carried out. Through hydrorefining, cracking, alkyl transfer and other means, benzene (B), toluene (T) and xylene (X) can be produced to the maximum extent. The refined light aromatic distillate oil can be fully utilized to increase its added value. Summary of the Invention

[0011] To address the problems of low BTX yield and low catalyst stability in the high-value chemical utilization of refined light aromatic-rich cracked distillate oils in existing technologies, this invention provides a novel hydrocracking catalyst. This hydrocracking catalyst is used for the production of BTX from highly stable refined light aromatic-rich distillate oils and exhibits excellent stability.

[0012] To achieve the aforementioned objective, according to a first aspect of the present invention, a hydrocracking catalyst is provided, comprising, by weight of the catalyst, the following components: a) 0.01%~1.5% Pd; b) 50%~90% ZSM-5; c) 5%~50% β-zeolite; d) 5%~20% adhesive; The amount of carbon deposited on the catalyst is 0.1% to 3% of the catalyst weight.

[0013] The hydrocracking catalyst provided by this invention has the advantage of long-term, high-stability operation. In this invention, the method for testing the coking characteristics of the catalyst is thermogravimetric analysis.

[0014] According to a preferred embodiment of the present invention, preferably, the dispersion of the active component Pd is greater than 18%, more preferably greater than 20%, and more preferably 20-35%.

[0015] In this invention, the range of adhesives that can be selected is relatively wide, and commonly used adhesives can all be used in this invention. For example, the adhesive can be selected from silicon dioxide and / or aluminum oxide.

[0016] In this invention, both ZSM-5 and β-zeolite can be used. For this invention, ZSM-5 powder is preferably in the hydrogen form, and the SiO2 / Al2O3 molar ratio is 20~200.

[0017] According to a preferred embodiment of the present invention, the β-zeolite is in the hydrogen form, and the SiO2 / Al2O3 molar ratio is 20~200.

[0018] According to a preferred embodiment of the present invention, the catalyst contains, by weight percentage, 0.1% to 1.5% Pd, 55% to 85% ZSM-5, 6% to 45% β-zeolite, and 5% to 15% binder.

[0019] Catalysts possessing the aforementioned characteristics of this invention can all be used in this invention. There are no special requirements for the catalyst preparation method. For this invention, a preferred catalyst preparation method includes: i) Prepare a composite carrier containing ZSM-5, β-zeolite and binder; ii) Prepare an impregnation solution containing a chelating agent, ethylene glycol oligomer, citric acid and Pd source as the impregnation solution; iii) The impregnation aqueous solution is impregnated and contacted with the composite carrier, then aged, and then the solid is dried in an inert atmosphere, calcined in a low oxygen inert atmosphere, and then reduced; The oxygen content in the low-oxygen inert atmosphere is less than 10% by volume, preferably less than 5% by volume.

[0020] In this invention, the range of selectable conditions for immersion contact is relatively wide. According to a preferred embodiment of this invention, the immersion temperature is 10~80℃.

[0021] The present invention does not have special requirements for the method of immersion contact, and various immersion contact methods can be used. According to a preferred embodiment of the present invention, the composite carrier is immersed by spraying.

[0022] In this invention, aging refers to maintaining the immersion contact for a period of time. According to a preferred embodiment of this invention, the aging time is 0.5 to 24 hours.

[0023] In this invention, the drying conditions can be selected from a wide range, and commonly used drying conditions can be used in this invention. For this invention, the preferred drying temperature is 30~200℃, preferably 110-120℃.

[0024] In this invention, the range of roasting conditions is relatively wide. The preferred roasting conditions for this invention include a temperature of 300~600℃ and a roasting time determined as needed. For this invention, the preferred roasting time is 0.5~24h.

[0025] In this invention, the reduction conditions can be selected from a wide range. The preferred reduction conditions for this invention include: the reduction peak temperature of the catalyst in the TPR hydrogen atmosphere before reduction is below 100°C, preferably 40-50°C.

[0026] The following is an illustrative description, but does not limit the scope of the invention. The reduction conditions include: the reducing agent is selected from one or more of hydrazine hydrate, sodium formate, and formaldehyde; the reduction temperature is below 100°C, preferably 20-100°C.

[0027] In this invention, the dry inert atmosphere can be any inert gas atmosphere. For this invention, the dry inert atmosphere is preferably one or more of nitrogen atmosphere and argon atmosphere, with nitrogen atmosphere being the most preferred.

[0028] In this invention, the oxygen content in the low-oxygen inert atmosphere during calcination is preferably 0.1-5% by volume, and the inert gas content is preferably 95-99.9% by volume. Any inert gas can be used in this invention. For this invention, the inert gas is preferably one or more of nitrogen and argon.

[0029] In this invention, the range of chelating agents is relatively wide. For this invention, the preferred chelating agent is selected from one or more of 1-hydroxyethylidene-1,1-diphosphonic acid, tetrasodium hydroxyethylidene diphosphonate (HEDP tetrasodium), aminotrimethylphosphonic acid (ATMPA), and ethylenediaminetetramethylene phosphoric acid (EDTMP), preferably 1-hydroxyethylidene-1,1-diphosphonic acid (HEDPA) and / or tetrasodium hydroxyethylidene diphosphonate (HEDP tetrasodium).

[0030] In this invention, the range of types of ethylene glycol oligomers is relatively wide. For this invention, the weight-average molecular weight of the ethylene glycol oligomers is preferably 200-600.

[0031] According to one embodiment of the present invention, the ethylene glycol oligomer is polyethylene glycol. In this invention, the composition of the impregnation solution can be selected from a wide range. For this invention, it is preferred that the content of chelating agent in every 100 ml of impregnation solution is 0.01~5 g, preferably 0.5~2 g.

[0032] According to a preferred embodiment of the present invention, the content of ethylene glycol oligomer and citric acid in each 100 ml of impregnation solution is 0.2 to 5 g.

[0033] According to a preferred embodiment of the present invention, the impregnation contact is an equal-volume impregnation contact.

[0034] In this invention, there are no special requirements for the preparation method of the composite carrier. According to a preferred embodiment of this invention, the preparation method of the composite carrier includes: (1) Mix the adhesive source, ZSM-5 powder, β zeolite powder and additives evenly to obtain mixture I; (2) Add the above mixture I to an acidic aqueous solution, wherein the acidic aqueous solution contains rare earth nitrates; after mixing, shape, dry and calcin.

[0035] According to a preferred embodiment of the present invention, the preparation method of the composite carrier includes: (1) firstly, mixing the binder, ZSM-5 powder, β zeolite powder and additives evenly to obtain mixture I; (2) adding the above mixture I to an acidic aqueous solution containing 1% to 6% by weight, wherein the weight ratio of mixture I to the acidic aqueous solution is 100:5 to 100:75, preferably 100:50 to 100:70, after kneading, extruding and molding, drying, and calcining at 450 to 650°C for 0.5 to 24 h to obtain the catalyst composite carrier.

[0036] According to a preferred embodiment of the present invention, preferably, the mass ratio of the adhesive, ZSM-5 powder, β-zeolite powder and additives added, based on alumina, is 1:(3-10):(0.4-3.5):(0.1-0.4).

[0037] According to a preferred embodiment of the present invention, preferably, the acidic aqueous solution also contains alkaline earth nitrates. The alkaline earth nitrates are calculated as alkaline earth oxides, and the acidic aqueous solution contains 1% to 6% acidic aqueous solution and 1% to 2% alkaline earth oxides as a weight percentage of the acidic aqueous solution.

[0038] According to a preferred embodiment of the present invention, the calcination conditions include: a temperature of 450~650℃ and a time of 0.5~24h.

[0039] In this invention, both ZSM-5 powder and β-zeolite powder can be used. For this invention, ZSM-5 powder is preferably in the hydrogen form, and the SiO2 / Al2O3 molar ratio is 20~200.

[0040] According to a preferred embodiment of the present invention, the β-zeolite powder is in the hydrogen form, and the SiO2 / Al2O3 molar ratio is 20~200.

[0041] In this invention, the range of types of adhesive sources is relatively wide, and commonly used adhesive sources can all be used in this invention. For this invention, the adhesive source is preferably selected from at least one of silica sol, water glass, boehmite, silica, and alumina sol.

[0042] In this invention, the range of selectable adjuvants is relatively wide, and commonly used adjuvants can all be used in this invention. For this invention, the preferred adjuvant is selected from at least one of methylcellulose, fennel powder, polyethylene glycol, calcium nitrate, potassium nitrate, and hydroxymethylcellulose.

[0043] In this invention, the range of types of acidic aqueous solutions is relatively wide, and commonly used acidic aqueous solutions can all be used in this invention. For this invention, it is preferred that the acidic substance in the acidic aqueous solution is selected from at least one of nitric acid, phosphoric acid, acetic acid, citric acid and tartaric acid.

[0044] According to a preferred embodiment of the present invention, the ZSM-5 powder is in the hydrogen form with a SiO2 / Al2O3 ratio of 50 to 300, the β-zeolite powder is in the hydrogen form with a SiO2 / Al2O3 ratio of 20 to 200, the binder is selected from at least one of silica sol, water glass, boehmite, silica, and alumina sol, and the additives are selected from at least one of methylcellulose, tianqing powder, polyethylene glycol, calcium nitrate, potassium nitrate, and hydroxymethylcellulose.

[0045] According to a preferred embodiment of the present invention, the acidic aqueous solution is selected from at least one of nitric acid, phosphoric acid, acetic acid, citric acid, and tartaric acid.

[0046] This invention provides the hydrocracking catalyst described herein for refining aromatic-rich distillate oils and cracking C9... + Ethylene tar, coal tar, catalytic light diesel oil or reformed C9 + Applications in hydrocracking.

[0047] This invention provides a method for producing BTX by hydrocracking of aromatic-rich distillate oil. The method includes: hydrocracking refined aromatic-rich light cracked distillate oil under hydrocracking reaction conditions in the presence of a catalyst, wherein the catalyst contains the hydrocracking catalyst described in this invention.

[0048] In this invention, the range of selectable hydrocracking conditions is relatively wide. According to a preferred embodiment of this invention, the hydrocracking conditions include a pressure of 2 to 8 MPa.

[0049] In this invention, the range of selectable hydrocracking conditions is relatively wide. According to a preferred embodiment of this invention, the hydrocracking conditions include: a fresh feed space velocity of 0.6~4.0 h⁻¹. -1 .

[0050] In this invention, the range of selectable hydrocracking conditions is relatively wide. According to a preferred embodiment of this invention, the hydrocracking conditions include a temperature of 300~500℃.

[0051] In this invention, the range of selectable hydrocracking conditions is relatively wide. According to a preferred embodiment of this invention, the hydrocracking conditions include a hydrogen-to-oil volume ratio of 500 to 2000.

[0052] According to a preferred embodiment of the present invention, a feedstock with an initial boiling point of 85-170°C, a final boiling point of 220-280°C, a sulfur content of <50 μg / mL, a nitrogen content of <10 μg / mL, and a monocyclic aromatic hydrocarbon content of >90 wt% is used for hydrocracking in a hydrogen atmosphere with a hydrocracking catalyst. The hydrocracking conditions include: a reactor inlet temperature of 300-500°C and a fresh feed space velocity of 0.6-4.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 500-2000, and the pressure is 2-8 MPa. The hydrocracking catalyst described in this invention exhibits excellent hydrocracking performance for aromatic-rich distillate oils with a final boiling point below 280°C and a monocyclic aromatic hydrocarbon content greater than 90% by weight, achieving a BTX liquid-phase yield greater than 55%. After 2000 hours of online operation, the BTX yield in the liquid-phase product is greater than 55%, with a toluene content greater than 50%.

[0053] Compared with the prior art, the beneficial effects of the present invention are as follows: The hydrocracking catalyst provided by this invention has high stability.

[0054] The preparation method of the hydrocracking catalyst of the present invention involves adding a chelating agent, citric acid and ethylene glycol oligomer during the impregnation process, drying in an inert atmosphere and calcining in a low oxygen-content inert atmosphere. This method simultaneously reduces the hydrogen atmosphere reduction temperature of the catalyst TPR, resulting in a catalyst with strong stability, long catalyst operating cycle and high BTX yield.

[0055] The hydrocracking catalyst provided by this invention effectively solves the problem of the inability to utilize refined light aromatic-rich cracked distillates at high added value for BTX production. It efficiently converts low-value-added light aromatic-rich cracked distillates into high-value-added BTX. This is suitable for refined light aromatic-rich cracked distillates with an initial boiling point of 85-170℃, a final boiling point of 220-280℃, a total aromatic content greater than 90%, a sulfur content <50ug / mL, and a nitrogen content <10ug / mL. The hydrocracking reaction conditions are: reactor inlet temperature 380-480℃, and fresh feed space velocity 0.6-4.0 h⁻¹. -1With a hydrogen-to-oil volume ratio of 500-2000 and a pressure of 2-8 MPa, the yield of total liquid phase products from initial hydrocracking is greater than 80%, and the yield of liquid phase product BTX is greater than 55%. After 2000 hours of online operation, the catalyst activity decreases little, and the yield of total liquid phase products is greater than 80%, of which the yield of liquid phase product BTX is greater than 55%, and the toluene content in BTX is greater than 50%, achieving good technical results. Attached Figure Description

[0056] Figure 1 The XRD patterns of the composite support and hydrocracking catalyst in Example 1 of this invention are shown below. Figure 2 This is a material distribution-online time plot showing the evaluation results of the hydrocracking catalyst in Example 1 of the present invention; Figure 3 The XRD patterns of the composite support and hydrocracking catalyst in Example 2 of this invention are shown below. Figure 4 The XRD patterns of the composite support and hydrocracking catalyst in Comparative Example 2 of the present invention are shown below. Detailed Implementation The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0057] The present invention will be further illustrated below by way of examples, but these examples are not intended to limit the scope of the present invention.

[0058] In this invention, the dispersion of the active component Pd is tested by hydrogen-oxygen titration.

[0059] R = [Pd] / [Pd] 总 =(2 / 3×V0×N A ×1 / 22400W / P) / (N A ×1 / M) In the formula: R-----the dispersion of Pd; [Pd]-----Number of Pd atoms on the surface; [Pd] 总 -----Total number of Pd atoms; V0 ----- Titration volume of hydrogen, mL; N A -----Avogadro's constant (6.023) ×10 23 ; W-----Sample mass, g; P-----Mass fraction of Pd in ​​the sample, % M-----The atomic weight of Pd is 106.4.

[0060] In this invention, the test method for TPR hydrogen atmosphere reduction is hydrogen-oxygen titration.

[0061] In this invention, the method for calculating the yield of liquid-phase products is as follows: Liquid phase product yield = W 液体产物 / W 原料 , W 液体产物 -----Weight of the liquid phase reaction products (in grams) after 24 hours of online processing; W 原料 ----Feed amount of refined light aromatic cracked distillate oil feedstock, in grams, for 24-hour online processing.

[0062] In this invention, the reduction peak temperature of the active component Pd is determined using the TPR programmed temperature reduction method. The reduction is carried out in a hydrogen atmosphere, with a heating rate of 10°C / minute, and the temperature is raised to 800°C.

[0063] Carbon deposition was measured using a Multi EA2000 carbon-sulfur analyzer from Jena, Germany. The catalyst was first dried at 150°C for 2 hours, and then tested at a combustion temperature of 900°C with 99.995% pure oxygen as the carrier gas. Spectroscopically pure CaCO3 powder with a carbon mass fraction of 12.00% was used as the standard.

[0064] In this invention, the method for determining the water absorption rate of the carrier is as follows: 5 grams of carrier are soaked in pure water for 5 minutes, then taken out and placed in a filter screen for 2 minutes to remove the surface moisture, which is the weight of the carrier after water absorption.

[0065] Water absorption rate = (W 吸水后载体 -W 载体 ) / W 载体 ×100%

Example 1

[0066] A soluble metal salt precursor was used to prepare an impregnation solution containing 1.2 g of Pd, with the solution volume controlled at 170 mL. 1.5 g of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDPA), 1.5 g of polyethylene glycol (molecular weight 200), and 2.0 g of citric acid were added to the impregnation solution and stirred until homogeneous. 198.8 g of a composite support was loaded with an equal volume of the impregnation solution using a rotary drum spray method at 20 °C. The mixture was aged for 16 hours, dried at 110 °C for 4 hours in a nitrogen atmosphere, and calcined at 400 °C for 6 hours in a nitrogen atmosphere containing 1.0% by volume of oxygen to obtain the catalyst. Reduction with a 5% sodium formate aqueous solution at 90 °C for 8 hours yielded the reduced catalyst. The composite support, catalyst preparation conditions, and catalyst carbon deposition are shown in Tables 1, 2, and 3.

[0067] XRD patterns of the composite support and catalyst are shown in [reference needed]. Figure 1 , Figure 1 The absence of characteristic peaks of the active component after loading the support indicates that the active component has small particle size and good dispersion on the support; the dispersion of the reduced catalyst Pd is 23.5%, indicating that the active component is well dispersed, easy to reduce, and has high catalyst activity.

[0068] Evaluation of raw materials: Refined light aromatic cracking feedstock: distillation range 165-255℃, sulfur content = 0.8ppm, nitrogen content = 0.6ppm; Raw material composition: non-aromatic 3.81 wt%; alkylbenzene 40.57 wt%; indene compounds 23.76 wt%; Tetrahydronaphthalenes 29.25 wt%; Naphthalenes 2.30 wt%; Benzene 0.31 wt%.

[0069] Reaction conditions: Reactor inlet temperature 330℃, fresh feed space velocity 1.8h. -1 The hydrogen-to-oil volume ratio is 800, and the pressure is 4.0 MPa. The evaluation results are shown in Table 4, and the material distribution-online time spectrum of the hydrocracking catalyst evaluation results is shown in Figure 1. Figure 2 , Figure 2 This indicates that the catalyst has good stability and a high BTX yield.

[0070]

Example 2

[0071] A soluble metal salt precursor was used to prepare an impregnation solution containing 1.2 g of Pd, with the solution volume controlled at 170 mL. 1.3 g of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDPA), 1.5 g of polyethylene glycol (molecular weight 200), and 2.0 g of citric acid were added to the impregnation solution and stirred until homogeneous. 198.8 g of the composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method at 60 °C. The mixture was aged for 16 hours, dried at 110 °C for 4 hours in a nitrogen atmosphere, and calcined at 400 °C for 6 hours in a nitrogen atmosphere containing 2.0% oxygen to obtain the catalyst. Reduction with a 5% sodium formate aqueous solution at 90 °C for 8 hours yielded the reduced catalyst. The composite support, catalyst preparation conditions, and catalyst carbon deposition are shown in Tables 1, 2, and 3.

[0072] XRD patterns of the composite support and catalyst are shown in [reference needed]. Figure 3 , Figure 3 The absence of characteristic peaks for the active component after loading onto the support indicates that the active component has a small particle size and good dispersion on the support. The dispersion of Pd in ​​the reduced catalyst is 22.8%, indicating that the active component is well dispersed, easy to reduce, and has high catalyst activity.

[0073] The raw materials and conditions for evaluation were the same as in Example 1, and the evaluation results are shown in Table 4.

[0074]

Example 3

[0075] A soluble metal salt precursor was used to prepare an impregnation solution containing 3.0 g of Pd, with the solution volume controlled at 170 mL. 1.5 g of tetrasodium hydroxyethylidene diphosphonate (HEDP tetrasodium), 2.0 g of polyethylene glycol (molecular weight 200), and 6.0 g of citric acid were added to the impregnation solution and stirred until homogeneous. 197.0 g of the composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method at 60 °C. The mixture was aged for 16 hours, dried at 110 °C for 4 hours in a nitrogen atmosphere, and calcined at 500 °C for 6 hours in an argon atmosphere containing 3.0% oxygen to obtain the catalyst. Reduction with hydrazine hydrate solution at 20 °C for 4 hours yielded the reduced catalyst. The composite support, catalyst preparation conditions, and catalyst carbon deposition are shown in Tables 1, 2, and 3.

[0076] XRD patterns of composite supports and catalysts Figure 1 and Figure 3 Similarly, the absence of characteristic peaks for the active component after loading onto the support indicates that the active component has a small particle size and good dispersion on the support. The dispersion of the reduced catalyst Pd is 25.8%, indicating that the active component is well dispersed, easy to reduce, and has high catalyst activity.

[0077] The raw materials and conditions for evaluation were the same as in Example 1, and the evaluation results are shown in Table 4.

[0078]

Example 4

[0079] A soluble metal salt precursor was used to prepare an impregnation solution containing 2.0 g of Pd, with the solution volume controlled at 170 mL. 1.0 g of aminotrimethylphosphonic acid (ATMPA), 1.0 g of ethylenediaminetetramethylene phosphoric acid (EDTMP), 3.0 g of polyethylene glycol (molecular weight 400), and 3.0 g of citric acid were added to the impregnation solution and stirred until homogeneous. 198.0 g of the composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method at 60 °C. The mixture was aged for 16 hours, dried at 110 °C for 4 hours in a nitrogen atmosphere, and calcined at 450 °C for 8 hours in a nitrogen atmosphere containing 1.5% oxygen to obtain the catalyst. Reduction with a 10% formaldehyde aqueous solution at 90 °C for 8 hours yielded the reduced catalyst. The composite support, catalyst preparation conditions, and catalyst carbon deposition are shown in Tables 1, 2, and 3.

[0080] XRD patterns of composite supports and catalysts Figure 1 and Figure 3 Similarly, the absence of characteristic peaks for the active component after loading onto the support indicates that the active component has a small particle size and good dispersion on the support. The dispersion of the reduced catalyst Pd is 35.0%, indicating that the active component is well dispersed, easy to reduce, and has high catalyst activity.

[0081] The raw materials and conditions for evaluation were the same as in Example 1, and the evaluation results are shown in Table 4.

[0082]

Example 5

[0083] A soluble metal salt precursor was used to prepare an impregnation solution containing 0.2 g of Pd, with the solution volume controlled at 170 mL. 2.0 g of tetrasodium hydroxyethylidene diphosphonate (HEDP tetrasodium), 0.5 g of polyethylene glycol (molecular weight 400), and 0.5 g of citric acid were added to the impregnation solution and stirred until homogeneous. 199.8 g of the composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method at 60 °C. The mixture was aged for 16 hours, dried at 110 °C for 4 hours in a nitrogen atmosphere, and calcined at 400 °C for 4 hours in a nitrogen atmosphere containing 4.0% oxygen to obtain the catalyst. Reduction with a 5% sodium formate aqueous solution at 90 °C for 8 hours yielded the reduced catalyst. The composite support, catalyst preparation conditions, and catalyst carbon deposition are shown in Tables 1, 2, and 3.

[0084] XRD patterns of composite supports and catalysts Figure 1 and Figure 3 Similarly, the absence of characteristic peaks for the active component after loading onto the support indicates that the active component has a small particle size and good dispersion on the support. The dispersion of the reduced catalyst Pd is 22.8%, indicating that the active component is well dispersed, easy to reduce, and has high catalyst activity.

[0085] The raw materials and conditions for evaluation were the same as in Example 1, and the evaluation results are shown in Table 4.

[0086]

Example 6

[0087] A soluble metal salt precursor was used to prepare an impregnation solution containing 0.8 g of Pd, with the solution volume controlled at 170 mL. 0.8 g of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDPA), 0.7 g of ethylenediaminetetramethylene phosphoric acid (EDTMP), 6.0 g of polyethylene glycol (molecular weight 400), and 0.5 g of citric acid were added to the impregnation solution and stirred until homogeneous. 199.2 g of the composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method at 60 °C. The mixture was aged for 16 hours, dried at 110 °C for 4 hours in a nitrogen atmosphere, and calcined at 600 °C for 6 hours in an argon atmosphere containing 0.5% oxygen to obtain the catalyst. Reduction with a 5% sodium formate aqueous solution at 90 °C for 8 hours yielded the reduced catalyst. The composite support, catalyst preparation conditions, and catalyst carbon deposition are shown in Tables 1, 2, and 3.

[0088] XRD patterns of composite supports and catalysts Figure 1 and Figure 3 Similarly, the absence of characteristic peaks for the active component after loading onto the support indicates that the active component has a small particle size and good dispersion on the support. The dispersion of the reduced catalyst Pd is 32.0%, indicating that the active component is well dispersed, easy to reduce, and has high catalyst activity.

[0089] The raw materials and conditions for evaluation were the same as in Example 1, and the evaluation results are shown in Table 4.

[0090]

Example 7

[0091] A soluble metal salt precursor was used to prepare an impregnation solution containing 1.2 g of Pd, with the solution volume controlled at 170 mL. 1.2 g of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDPA), 1.3 g of tetrasodium hydroxyethylidene diphosphonate (HEDP tetrasodium), 3.0 g of polyethylene glycol (molecular weight 600), and 1.5 g of citric acid were added to the impregnation solution and stirred until homogeneous. 198.8 g of the composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method at 60 °C. The mixture was aged for 16 hours, dried at 110 °C for 4 hours in a nitrogen atmosphere, and calcined at 450 °C for 6 hours in a nitrogen atmosphere containing 0.8% oxygen to obtain the catalyst. Reduction with a 5% sodium formate aqueous solution at 90 °C for 8 hours yielded the reduced catalyst. The composite support, catalyst preparation conditions, and catalyst carbon deposition are shown in Tables 1, 2, and 3.

[0092] XRD patterns of composite supports and catalysts Figure 1 and Figure 3 Similarly, the absence of characteristic peaks for the active component after loading onto the support indicates that the active component has a small particle size and good dispersion on the support. The dispersion of the reduced catalyst Pd is 23.5%, indicating that the active component is well dispersed, easy to reduce, and has high catalyst activity.

[0093] The raw materials and conditions for evaluation were the same as in Example 1, and the evaluation results are shown in Table 4.

[0094]

Example 8

[0095] A soluble metal salt precursor was used to prepare an impregnation solution containing 1.2 g of Pd, with the solution volume controlled at 170 mL. 1.2 g of tetrasodium hydroxyethylidene diphosphonate (HEDP tetrasodium), 2.0 g of aminotrimethylphosphonic acid (ATMPA), 2.0 g of polyethylene glycol (molecular weight 600), and 2.0 g of citric acid were added to the impregnation solution and stirred until homogeneous. 198.8 g of the composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method at 60 °C. The mixture was aged for 16 hours, dried at 110 °C for 4 hours in a nitrogen atmosphere, and calcined at 550 °C for 6 hours in a nitrogen atmosphere containing 1.0% oxygen to obtain the catalyst. Reduction with a 5% sodium formate aqueous solution at 90 °C for 8 hours yielded the reduced catalyst. The composite support, catalyst preparation conditions, and catalyst carbon deposition are shown in Tables 1, 2, and 3.

[0096] XRD patterns of composite supports and catalysts Figure 1 and Figure 3 Similarly, the absence of characteristic peaks for the active component after loading onto the support indicates that the active component has a small particle size and good dispersion on the support. The dispersion of the reduced catalyst Pd is 22.0%, indicating that the active component is well dispersed, easy to reduce, and has high catalyst activity.

[0097] The raw materials and conditions for evaluation were the same as in Example 1, and the evaluation results are shown in Table 4.

[0098]

Example 9

[0099] A soluble metal salt precursor was used to prepare an impregnation solution containing 1.2 g of Pd, with the solution volume controlled at 170 mL. 0.8 g of tetrasodium hydroxymethylene diphosphonate (HEDP tetrasodium), 0.6 g of ethylenediaminetetramethylene phosphoric acid (EDTMP), 4.5 g of polyethylene glycol (molecular weight 300), and 3.5 g of citric acid were added to the impregnation solution and stirred until homogeneous. 198.8 g of the composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method at 60 °C. The mixture was aged for 16 hours, dried at 110 °C for 4 hours in a nitrogen atmosphere, and calcined at 300 °C for 6 hours in a nitrogen atmosphere containing 0.2% oxygen to obtain the catalyst. Reduction with a 5% sodium formate aqueous solution at 90 °C for 8 hours yielded the reduced catalyst. The composite support, catalyst preparation conditions, and catalyst carbon deposition are shown in Tables 1, 2, and 3.

[0100] XRD patterns of composite supports and catalysts Figure 1 and Figure 3 Similarly, the absence of characteristic peaks for the active component after loading onto the support indicates that the active component has a small particle size and good dispersion on the support. The dispersion of the reduced catalyst Pd is 20.1%, indicating that the active component is well dispersed, easy to reduce, and has high catalyst activity.

[0101] The raw materials and conditions for evaluation were the same as in Example 1, and the evaluation results are shown in Table 4.

[0102]

Example 10

[0103] A soluble metal salt precursor was used to prepare an impregnation solution containing 1.2 g of Pd, with the solution volume controlled at 170 mL. 0.5 g of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDPA), 0.6 g of aminotrimethylphosphonic acid (ATMPA), 1.6 g of polyethylene glycol (molecular weight 300), and 0.6 g of citric acid were added to the impregnation solution and stirred until homogeneous. 198.8 g of the composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method at 60 °C. The mixture was aged for 16 hours, dried at 110 °C for 4 hours in a nitrogen atmosphere, and calcined at 500 °C for 3 hours in a nitrogen atmosphere containing 1.2% oxygen to obtain the catalyst. The reduced catalyst was obtained by reduction with a 5% sodium formate aqueous solution at 100 °C for 6 hours. The composite support, catalyst preparation conditions, and catalyst carbon deposition are shown in Tables 1, 2, and 3.

[0104] XRD patterns of composite supports and catalysts Figure 1 and Figure 3 Similarly, the absence of characteristic peaks for the active component after loading onto the support indicates that the active component has a small particle size and good dispersion on the support. The dispersion of the reduced catalyst Pd is 23.2%, indicating that the active component is well dispersed, easy to reduce, and has high catalyst activity.

[0105] The raw materials and conditions for evaluation were the same as in Example 1, and the evaluation results are shown in Table 4.

[0106]

Comparative Example 1

[0107] A soluble metal salt precursor was used to prepare an impregnation solution containing 1.2 g of Pd, with the solution volume controlled at 170 mL. 1.5 g of polyethylene glycol (molecular weight 200) and 2.0 g of citric acid were added to the impregnation solution and stirred until homogeneous. 198.8 g of a composite support was then loaded with an equal volume of the impregnation solution using a rotary drum spray method at 20 °C. The mixture was aged for 16 hours, dried at 110 °C in a nitrogen atmosphere for 4 hours, and calcined at 400 °C in air for 6 hours to obtain the catalyst. Reduction with a 5% sodium formate aqueous solution at 90 °C for 8 hours yielded the reduced catalyst. The composite support, catalyst preparation conditions, and catalyst carbon deposition are shown in Tables 1, 2, and 3.

[0108] The dispersion of Pd in ​​the reduced catalyst is 7.8%.

[0109] The raw materials and conditions for evaluation were the same as in Example 1, and the evaluation results are shown in Table 4.

[0110] [Comparative Example 2] 900g of ZSM-5 molecular sieve powder with a hydrogen form SiO2 / Al2O3 ratio of 25, 100g of boehmite containing alumina, 15g each of methylcellulose and Tianqing powder were selected and mixed evenly for later use. Then, 7g of nitric acid and 5g of citric acid were added to 600g of water and dissolved evenly. The solution was poured into the above mixed powder and kneaded for 35 minutes. The mixture was then extruded into strips, left to stand for 12 hours, dried at 110℃ for 6 hours, and then calcined in a muffle furnace at 600℃ for 5 hours to obtain the composite carrier with a water absorption rate of 99.1%.

[0111] A soluble metal salt precursor was used to prepare an impregnation solution containing 1.2 g of Pd, with the solution volume controlled at 170 mL. 1.5 g of 1-hydroxyethylidene-1,1-diphosphonic acid (HEDPA), 1.5 g of polyethylene glycol (molecular weight 200), and 2.0 g of citric acid were added to the impregnation solution and stirred until homogeneous. 198.8 g of a composite support was loaded with an equal volume of the impregnation solution using a rotary drum spray method at 20 °C. The mixture was aged for 16 hours, dried at 110 °C for 4 hours in a nitrogen atmosphere, and calcined at 400 °C for 6 hours in a nitrogen atmosphere containing 1.0% oxygen to obtain the catalyst. Reduction with a 5% sodium formate aqueous solution at 90 °C for 8 hours yielded the reduced catalyst. The composite support, catalyst preparation conditions, and catalyst carbon deposition are shown in Tables 1, 2, and 3.

[0112] XRD patterns of the composite support and catalyst are shown in [reference needed]. Figure 4 , Figure 4 The absence of characteristic peaks for the active component after loading onto the support indicates that the active component has a small particle size and good dispersion on the support. The dispersion of the reduced catalyst palladium is 6.9%.

[0113] The raw materials and conditions for evaluation were the same as in Example 1, and the evaluation results are shown in Table 4.

[0114] Table 1. Preparation conditions of composite carriers

[0115] Table 2 Catalyst preparation conditions, carbon deposition amount, and Pd dispersion

[0116] As can be seen from the results in Table 2, the catalysts prepared in Examples 1-10 have a much higher dispersion than the comparative example, and their reduction temperatures are also significantly lower than those of the comparative example. This indicates that the catalysts prepared by the method of the present invention have the effects of high dispersion of active components and low reduction temperature.

[0117] Table 3. Amounts of catalyst chelating agents and additives added

[0118] Table 4 Catalyst Evaluation Results

[0119] Because the support uses a suitable combination of ZSM-5 and β-zeolite, and the loading technology of this invention is employed, after loading the active component, the selective hydrocracking product is predominantly BTX; moreover, the toluene content in the BTX product of this invention exceeds 50%, exhibiting significant toluene selectivity. By controlling the carbon content on the catalyst surface through carbonization technology, the catalyst's online stability after 2000 hours is significantly improved.

[0120] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A hydrocracking catalyst, characterized in that, The catalyst comprises the following components by total weight: a) 0.01%~1.5% Pd; b) 50%~90% ZSM-5; c) 5%~50% β-zeolite; d) 5%~20% adhesive; The sum of the contents of all components is 100%; The amount of carbon deposited on the catalyst is 0.1% to 3% of the catalyst weight, and the dispersion of the active component Pd is greater than 18%. Wherein, the dispersion of the active component Pd is R = [Pd] / [Pd] 总， [Pd]-----Number of Pd atoms on the surface; [Pd] 总 -----Total number of Pd atoms.

2. The catalyst according to claim 1, wherein, The dispersion of the active component Pd is greater than 20%; and / or The adhesive is selected from silica and / or alumina; and / or ZSM-5 is in the hydrogen form, with a SiO2 / Al2O3 molar ratio of 20~200; and / or β-zeolite is in the hydrogen form, with a SiO2 / Al2O3 molar ratio of 20–200; and / or In the catalyst, by total weight, Pd is 0.1%~1.5%, ZSM-5 is 55%~85%, β zeolite is 6%~45%, and binder content is 5%~15%.

3. The catalyst according to claim 2, wherein, The dispersion of the active component Pd is 20-35%.

4. A method for preparing the catalyst according to any one of claims 1-3, wherein, The method includes: i) Prepare a composite carrier containing ZSM-5, β-zeolite and binder; ii) Prepare an impregnation solution containing a chelating agent, ethylene glycol oligomer, citric acid and Pd source as the impregnation solution; iii) The impregnation solution is impregnated and contacted with the composite carrier, then aged, and then the solid is dried in an inert atmosphere, calcined in a low oxygen inert atmosphere, and then reduced; The oxygen content in the low-oxygen inert atmosphere is less than 10% by volume.

5. The preparation method according to claim 4, wherein, The oxygen content in the low-oxygen inert atmosphere is below 5% by volume.

6. The preparation method according to claim 4, wherein, Step iii), the conditions for immersion contact include: The impregnation temperature is 10~80℃; and / or The composite carrier is impregnated by spraying; and / or The aging time is 0.5~24 hours.

7. The preparation method according to claim 4, wherein, Step iii). Drying conditions include: a temperature of 30~200℃; and / or The roasting conditions include: a temperature of 300~600℃, and / or a time of 0.5~24h; and / or The conditions for reduction include: the reducing agent is selected from one or more of hydrazine hydrate, sodium formate, and formaldehyde, and the reduction temperature is below 100℃.

8. The preparation method according to claim 4, wherein, Step iii). Drying conditions include: a temperature of 110-120℃; and / or The conditions for reduction include a reduction temperature of 20-100℃.

9. The preparation method according to claim 8, wherein, Step iii). The conditions for reduction include a reduction temperature of 40-50℃.

10. The preparation method according to claim 4, wherein, Step iii). The dry, inert atmosphere is one or more of nitrogen and argon; and / or The oxygen content in the low-oxygen inert atmosphere during roasting is 0.1-5% by volume, and the inert gas content is 95-99.9% by volume.

11. The preparation method according to claim 10, wherein, Step iii). The dry, inert atmosphere is a nitrogen atmosphere; and / or In the low-oxygen inert atmosphere of the roasting process, the inert gas is one or more of nitrogen and argon.

12. The preparation method according to claim 4, wherein, The chelating agent is selected from one or more of 1-hydroxyethylidene-1,1-diphosphonic acid, tetrasodium hydroxyethylidene diphosphonate, aminotrimethylphosphonic acid, and ethylenediaminetetramethylene phosphoric acid; and / or The weight-average molecular weight of ethylene glycol oligomers is 200-600; and / or The ethylene glycol oligomer is polyethylene glycol; and / or The chelating agent content is 0.01~5 g per 100 ml of impregnation solution; and / or The content of ethylene glycol oligomer and citric acid in each 100 ml of impregnation solution is 0.2-5 g each; and / or The impregnation contact is an equal-volume impregnation contact.

13. The preparation method according to claim 12, wherein, The chelating agent is selected from 1-hydroxyethylidene-1,1-diphosphonic acid and / or tetrasodium hydroxyethylidene bisphosphonate; and / or The chelating agent content is 0.5 to 2 grams per 100 ml of impregnation solution.

14. The preparation method according to claim 4, wherein, Methods for preparing composite carriers include: (1) Mix the adhesive source, ZSM-5 powder, β zeolite powder and additives evenly to obtain mixture I; (2) Add the above mixture I to an acidic aqueous solution, knead and shape, dry and calcin.

15. The preparation method according to claim 14, wherein, The concentration of acidic substances in the acidic aqueous solution is 1% to 6% by weight; and / or The weight ratio of mixture I to the acidic aqueous solution is 100:5 to 100:75; and / or In step (2), the roasting conditions include: a temperature of 450~650℃ and a time of 0.5~24h.

16. The preparation method according to claim 15, wherein, The weight ratio of mixture I to the acidic aqueous solution is 100:50 to 100:

70.

17. The preparation method according to claim 14, wherein, ZSM-5 powder is in the hydrogen form, with a SiO2 / Al2O3 molar ratio of 20~200; and / or β-zeolite powder is in the hydrogen form, with a SiO2 / Al2O3 molar ratio of 20~200; and / or The adhesive source is selected from at least one of silica sol, water glass, boehmite, silica, and alumina sol; and / or The additives are selected from at least one of methylcellulose, fennel powder, polyethylene glycol, calcium nitrate, potassium nitrate, and hydroxymethylcellulose; The acidic substance in the acidic aqueous solution is selected from at least one of nitric acid, phosphoric acid, acetic acid, citric acid and tartaric acid.

18. The hydrocracking catalyst according to any one of claims 1-3 in the refining of rich aromatic light cracked distillate oil and cracking C9... + Ethylene tar, coal tar, catalytic light diesel oil or reformed C9 + Applications in hydrocracking; among them, The content of monocyclic aromatic hydrocarbons in refined aromatic light cracked distillate oil is >90wt%.

19. A method for producing BTX by hydrocracking of refined aromatic light cracked distillate oil, characterized in that, The method includes: In the presence of a catalyst, under hydrocracking reaction conditions, a refined aromatic light cracked distillate is subjected to hydrocracking, wherein the catalyst contains the hydrocracking catalyst according to any one of claims 1-3, and the content of monocyclic aromatic hydrocarbons in the refined aromatic light cracked distillate is >90 wt%.

20. The method according to claim 19, wherein, The refined rich-aromatic light cracked distillate oil includes: initial boiling point of 85~170℃, final boiling point of 220~280℃, sulfur content <50ug / mL, and nitrogen content <10ug / mL; the hydrocracking reaction conditions include: reactor inlet temperature of 300~500℃, and fresh feed space velocity of 0.6~4.0h. -1 The hydrogen-to-oil volume ratio is 500-2000, and the pressure is 2-8 MPa.

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